Locking mechanism for lift arm assembly

ABSTRACT

A locking mechanism adapted for use with a lift arm assembly. The lift arm assembly is connected to and operatively associated with a lift actuator for movement between raised and lowered positions. The lift actuator having a tubular body and an extendable rod. The locking mechanism includes a lockbar having a proximal end and a distal end opposite to the proximal end. The proximal end is configured to be pivotally connected to the lift arm assembly and movable between an inoperative position and an operative position to selectively prevent retraction of the rod within the tubular body of the lift actuator. The locking mechanism further includes a release lever pivotally connected at the distal end of the lockbar and is adapted to move between a rest position and a working position.

TECHNICAL FIELD

The present disclosure relates generally to a releasable lift arm locking mechanism for maintaining a lift actuator in an extended position operatively associated with a lift arm or a boom of a machine, and more particularly to the ability to release the locking mechanism with a limited intervention from an operator.

BACKGROUND

A lift arm locking mechanism generally holds a lift arm of a loader (e.g., a skid steer loader, a wheel loader, a track loader, and etc.) in a raised position for repair or servicing. U.S. Pat. No. 6,149,374 discloses one such locking mechanism having a release lever connected to a lift cylinder which has a notched end portion for forcing a lock bar out of bearing engagement with the lift cylinder. The location of the release lever on the lift cylinder and the interaction with the lock bar during disengagement from the lift cylinder provides a releasable locking mechanism that can be controlled by an operator seated on the machine. However, there is still room for improvement in the art.

SUMMARY

In an aspect, the present disclosure describes a locking mechanism adapted for use with a lift arm assembly. The lift arm assembly is connected to and operatively associated with a lift actuator for movement between raised and lowered positions. The lift actuator has a tubular body and an extendable rod. The locking mechanism includes a lockbar having a proximal end and a distal end opposite to the proximal end. The proximal end is configured to be pivotally connected to the lift arm assembly and movable to an inoperative position and an operative position to selectively prevent retraction of the rod within the tubular body of the lift actuator. The locking mechanism further includes a release lever pivotally connected at the distal end of the lockbar and is adapted to move between a rest position and a working position.

Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a skid steer loader and a locking mechanism, according to an aspect of the present disclosure;

FIG. 2 illustrates a side view of a lift arm assembly and the locking mechanism of FIG. 1;

FIGS. 3 and 4 illustrate steps of using the locking mechanism to lock the lift arm assembly of the skid steer loader in a raised position; and

FIGS. 5 to 9 illustrate steps of using the locking mechanism to release the lift arm assembly of the skid steer loader to be moved to a lowered position.

DETAILED DESCRIPTION

The present disclosure discloses a lift arm locking mechanism adapted for use with a lift arm or a boom of a machine which is releasable with a limited intervention from an operator. FIG. 1 illustrates a side view of a machine 100, such as a skid steer loader, in which various embodiments of the present disclosure may be implemented. Although, the machine 100 is embodied as the skid steer loader 100, those skilled in the art will understand that the present disclosure may be applicable to other types of machines, for example, a compact track loader, a multiple terrain loader, or any other type of machines having a lift arm or a boom. In the illustrated embodiment, the skid steer loader 100 includes a frame 102 to support various parts of the skid steer loader 100 like a power source, for example an engine, lift linkages, power trains, hydraulic pumps, motors, valves, hydraulic lines, and a hydraulic tank. The frame 102 may include a front end portion 104 and a rear end portion 106 and supported by a plurality of wheels 108.

A cab 110 is mounted on the front end portion 104 of the frame 102 enclosing an operating compartment 112. The operating compartment 112 may include a plurality of control devices, such as joysticks, user interfaces, controls and other type of display and input devices to control various operations associated with the skid steer loader 100. The frame 102 may also support left and right upright tower assemblies 114 (only one side is shown) which are positioned on the rear end portion 106. Left and right lift arm assemblies 116 (only one side is shown) are pivotally mounted on the respective corresponding left and right upright tower assemblies 114 and configured to move an implement 118, such as a bucket, between a lowered position 120 and a raised position 122 (the raised position 122 shown by dash lines). In an embodiment, each lift arm assembly 116 may include a lift arm 124 and a pair of curved, side plate portions 126 connected in a spaced relationship on the lift arm 124. The implement 118 is connected to the lift arm assemblies 116 at the side plate portions 126 via a coupler or by any other suitable means and is operable in a well known manner. It will be apparent to a person having ordinary skill in the art that in various other embodiments, the implement 118 may include a blade, a fork, a grapple, a hammer, or any other work tool type implement.

Further, left and right lift actuators 128 are used to lower or raise the respective corresponding left and right lift arm assemblies 116. The lift actuators 128 may include conventional hydraulic or pneumatic cylinders or any other type of known linear actuators. The left and right lift arm assemblies 116 and respective lift actuators 128 may be substantially identical to each other, however only the left lift arm assembly 116 and lift actuator 128 are discussed in further details herein. It should be understood that although the present disclosure is used in conjunction with the lift arm assembly 116 of the skid steer loader 100, it could easily be modified to function with any lift arm assembly or a mechanism utilizing a lift actuator.

In an exemplary embodiment, the lift actuator 128 is a conventional hydraulic cylinder having a tubular body 130 with a proximal end 132 pivotally mounted to the upright tower assembly 114 and a distal end 134 opposite the proximal end 132. The lift actuator 128 further includes a rod 136 with a proximal end 138 pivotally mounted on a pivot pin 140 provided on the pair of side plate portions 126 of the lift arm assembly 116. Alternatively, the proximal end 138 of the rod 136 may be pivotally mounted on a pivot pin provided on the lift arm 124. A distal end 142 (see FIG. 2) of the rod 136 opposite the proximal end 138 is connected with and extendable from the tubular body 130 in a well known manner. The tubular body 130 of the lift actuator 128 has a diameter which is greater than the diameter of the rod 136 to define a shoulder portion 144 at the distal end 134 of the tubular body 130.

According to an embodiment of the present disclosure, a releasable locking mechanism 146 which is adapted to be used with the lift arm assembly 116 is provided. The locking mechanism 146 may include lockbar 148 having a proximal end 150 pivotally connected on the pivot pin 140, and a distal end 152 opposite to the proximal end 150. It will be understood to a person having ordinary skill in the art that, the lockbar 148 may have a channel shape including a top wall and a pair of spaced side walls which extend downwardly from the top wall. The side walls at the distal end 152 are spaced apart by a distance smaller than the diameter of the tubular body 130 of the lift actuator 128 and greater than the diameter of the rod 136 of the lift actuator 128. In an embodiment, the proximal end 150 have a pair of bifurcated legs pivotally connected on the pivot pin 140 at the pair of side plate portions 126 and straddle the rod 136. Further, a release lever 154 is pivotally connected at the distal end 152 of the lockbar 148.

Referring now to FIG. 2, the locking mechanism 146 may be explained in detail hereafter. The lockbar 148 is movable between an inoperative position, as shown in FIGS. 1 and 2, and an operative position, as shown in FIGS. 3 to 9. A stow bar 156 is connected in any suitable manner, such as welding, to the lift arm 124 of the lift arm assembly 116 and extends downwardly from a bottom surface thereof. The stow bar 156 has a defined opening 158 (see FIG. 3) therethrough. In an embodiment, a plurality of openings 160 provided on the lockbar 148 are configured to be aligned with the opening 158 provided on the stow bar 156. The aligned openings 158, 160 may be releasably locked by a pin assembly 162 to store the lockbar 148 in the inoperative position. The pin assembly 162 may include a pin with a transverse bore configured to extend through the aligned openings 158, 160, and a retaining clip configured to extend through the transverse bore to provide a positive lock.

The release lever 154 includes a pivot end portion 164, and a free end portion 166 opposite to the pivot end portion 164. The pivot end portion 164 of the release lever 154 is pivotally connected at the distal end 152 of the lockbar 148. Moreover, the lockbar 148 may further include securing slots 168 provided at the distal end 152. The lockbar 148 and the release lever 154 may be made of a rigid material such as metallic alloys, composites, or any similar materials of desired rigidity to support lift arm assemblies 116. As illustrated in FIG. 2, in the inoperative position, the release lever 154 is disposed adjacent and parallel with respect to the lockbar 148. However, it will be appreciated that in the operative position, the release lever 154 may pivot about the pivot end portion 164.

INDUSTRIAL APPLICABILITY

The industrial applicability of the releasable locking mechanism 146 associated with the lift arm assembly 116 described herein will be readily appreciated from the foregoing discussion. Although shown as the lift arm assembly 116 of the skid steer loader 100, it should also be understood that the locking mechanism 146 may be used on any machine which utilizes lift arm assemblies. For example, any type of lifting device or machine associated with mining, construction, and other industrial applications and having a lift arm or boom which is operatively connected to a lift actuator for movement between raised and lowered positions, may embody locking mechanism 146.

The locking mechanism 146 enables the lift actuator 128 to be locked in an extended position in order to hold the lift arm assembly 116 in the raised position 122 during maintenance or repair of the skid steer loader 100. Further, the locking mechanism 146 enables the locked lift actuator 128 to be released in order to bring the lift arm assembly 116 to the lowered position 120. An operator (not shown) cooperates manually with the locking mechanism 146 to accomplish the locking and releasing of the lift actuator 128 when the lift arm assembly 116 is in the lowered position 120 or when the lift actuator 128 is locked in the raised position 122 of the lift arm assembly 116.

During normal operation of the skid steer loader 100, the lockbar 148 is stowed in the inoperative position, as illustrated in FIGS. 1 and 2. As described above, in the inoperative position the stow bar 156 holds the lockbar 148 via the pin assembly 162 extending through the opening 158, 160 provided in the stow bar 156 and the lockbar 148, respectively. Further, in the inoperative position the release lever 154 is maintained in a rest position disposed adjacent and substantially parallel with respect to the lockbar 148, as illustrated in FIGS. 1 and 2.

The locking of the lift actuator 128 is accomplished by moving the lockbar 148 from the inoperative position to the operative position while the lift arm assembly 116 is in the lowered position 120. As illustrated in FIG. 3, to move the lockbar 148 to the operative position the pin assembly 162 extending through the opening 158, 160 is removed to allow the distal end 152 of the lockbar 148 to drop and rest on the tubular body 130 of the lift actuator 128. The rod 136 is extended so that the lift arm assembly 116 is beyond the raised position 122 of the lift arm assembly 116. During the extension of the rod 136, the lockbar 148 moves along the tubular body 130 of the lift actuator 128 until the distal end 152 of the lockbar 148 drops onto the rod 136. The rod 136 is retracted so that the distal end 152 of the lockbar 148 contacts the shoulder portion 144 of the lift actuator 128, as illustrated in FIG. 4. Thus, the lift actuator 128 is secured in a locked position while the lockbar 148 prevents any further refraction of the rod 136. Further, a pin assembly 170 extending through the securing slots 168, provided at the distal end 152 of the lockbar 148, traps the rod 136 within the channel shape of the lockbar 148. The pin assembly 170 retains the lockbar 148 in the operative position during maintenance or repair of the skid steer loader 100. The pin assembly 170 may be substantially identical to the pin assembly 162 and include a pin with a transverse bore configured to extend through the securing slots 168, and a retaining clip configured to extend through the transverse bore to provide a positive lock, holding the lockbar 148 around the rod 136.

To release to the locked lift actuator 128, the pin assembly 170 extending through the securing slots 168 is removed. The operator pivots the release lever 154 about the pivot end portion 164 to move the release lever 154 from the rest position to a working position. In the working position, the free end portion 166 of the release lever 154 is seated on the tubular body 130 of the lift actuator 128, as illustrated in FIG. 5. Now again, the rod 136 of the lift actuator 128 is extended so that the release lever 154 rides along the tubular body 130 and the free end portion 166 drops and contacts the rod 136, as illustrated in FIG. 6. The rod 136 of the lift actuator 128 is then retracted to force the free end portion 166 of the release lever 154 against the shoulder portion 144 of the lift actuator 128 and lift the lockbar 148 out of engagement with the rod 136 of the lift actuator 128, as seen in FIGS. 7 and 8. The rod 136 of the lift actuator 128 is retracted further to move the lift arm assembly 116 towards the lowered position 120. During retraction of the rod 136, the lockbar 148 and the release lever 154 are forced upward and rearward, substantially into the rest position, as illustrated in FIG. 9. Simultaneously, the lockbar 148 will drop onto the tubular body 130 of the lift actuator 126 for movement therealong until the retraction of the rod 136 is complete. The release lever 154 may then be pivoted about the pivot end portion 164 to the rest position and the lockbar 148 may then be stowed in the inoperative position, as seen in FIG. 2.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed locking mechanism without departing from the scope of the disclosure. Other embodiments of the lift arm locking mechanism will be apparent to those skilled in the art from consideration of the specification and practice of the system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A locking mechanism adapted for use with a lift arm assembly which is connected to and operatively associated with a lift actuator for movement between raised and lowered positions, the lift actuator having a tubular body and an extendable rod, the locking mechanism comprising: a lockbar having a proximal end and a distal end opposite to the proximal end, the proximal end configured to be pivotally connected to the lift arm assembly and movable between an inoperative position and an operative position to selectively prevent retraction of the extendable rod within the tubular body of the lift actuator; and a release lever pivotally connected at the distal end of the lockbar, the release lever is adapted to move between a rest position and a working position.
 2. The locking mechanism of claim 1, wherein the release lever includes a pivot end portion and a free end portion opposite to the pivot end portion, the pivot end portion of the release lever is pivotally connected at the distal end of the lockbar.
 3. The locking mechanism of claim 2, wherein in the rest position the free end portion of the release lever is disposed adjacent and substantially parallel with respect to the lockbar.
 4. The locking mechanism of claim 2, wherein in the working position the free end portion of the release lever is configured to be seated on the lift actuator.
 5. The locking mechanism of claim 1, wherein the lockbar includes a plurality of openings which are configured to be aligned with an opening provided on a stow bar extending from the lift arm assembly.
 6. The locking mechanism of claim 5, wherein the openings provided on the lockbar and the stow bar are configured to be releasably locked by a pin assembly to store the lockbar in the inoperative position.
 7. The locking mechanism of claim 1, wherein the lockbar includes securing slots provided at the distal end.
 8. The locking mechanism of claim 7, wherein the securing slots are configured to be releasably locked by a pin assembly to retain the lockbar in the operative position.
 9. A machine comprising: a frame; a lift arm assembly pivotally coupled to the frame; a lift actuator operatively connected with the lift arm assembly for moving the lift arm assembly between raised and lowered positions, the lift actuator having a tubular body and an extendable rod, the tubular body pivotally coupled to the frame and the rod pivotally connected to the lift arm assembly; and a locking mechanism adapted for use with a lift arm assembly, the locking mechanism including: a lockbar having a proximal end and a distal end opposite to the proximal end, the proximal end configured to be pivotally connected to the lift arm assembly and movable between an inoperative position and an operative position to selectively prevent refraction of the extendable rod within the tubular body of the lift actuator; and a release lever pivotally connected at the distal end of the lockbar, the release lever is adapted to move between a rest position and a working position.
 10. The machine of claim 9, wherein the release lever includes a pivot end portion and a free end portion opposite to the pivot end portion, the pivot end portion of the release lever is pivotally connected at the distal end of the lockbar.
 11. The machine of claim 10, wherein in the rest position the free end portion of the release lever is disposed adjacent and substantially parallel with respect to the lockbar.
 12. The machine of claim 10, wherein in the working position the free end portion of the release lever is seated on the lift actuator.
 13. The machine of claim 9, wherein the lockbar includes a plurality of openings which are configured to be aligned with an opening provided on a stow bar extending from the lift arm assembly.
 14. The machine of claim 13, wherein the openings provided on the lockbar and the stow bar are configured to be releasably locked by a pin assembly to store the lockbar in the inoperative position.
 15. The machine of claim 9, wherein the lockbar includes securing slots provided at the distal end.
 16. The machine of claim 15, wherein the securing slots are configured to be releasably locked by a pin assembly to retain the lockbar in the operative position.
 17. A lifting device comprising: a lift arm assembly pivotally coupled to a frame; a lift actuator operatively connected with the lift arm assembly for moving the lift arm assembly between raised and lowered positions; and a locking mechanism adapted for use with a lift arm assembly, the locking mechanism comprising: a lockbar having a proximal end and a distal end opposite to the proximal end, the proximal end configured to be pivotally connected to the lift arm assembly and movable between an inoperative position and an operative position to selectively prevent retraction of an extendable rod within a tubular body of the lift actuator; and a release lever pivotally connected at the distal end of the lockbar, the release lever is adapted to move between a rest position and a working position.
 18. The lifting device of claim 17, wherein the release lever includes a pivot end portion and a free end portion opposite to the pivot end portion, the pivot end portion of the release lever is pivotally connected at the distal end of the lockbar.
 19. The lifting device of claim 18, wherein in the rest position the free end portion of the release lever is disposed adjacent and substantially parallel with respect to the lockbar.
 20. The lifting device of claim 18, wherein in the working position the free end portion of the release lever is seated on the lift actuator. 